Joyrex

Fixed it! It took maybe 2-3 hours of learning how to use the multimeter for testing connectivity and voltage, and then learning how to use the multimeter in an effective way when trying to narrow down my problem. To review, I soldered the whole kit together, but when I plugged it in there was no activity. The board should do a quick POST and then the green light should light up (and the screen will display stuff if it's plugged in).

I had determined I was getting a proper 9V into the first voltage regulator, and a proper 5V out from it. The second voltage regulator didn't seem to have anything incoming or outgoing, though. I ran through almost every A->B connection I could on the board, testing connectivity, all good. I tried tracing paths on the board, checking voltage between them. I never went end to end though, as I would get distracted and look at a different path or I strayed too far from the regulator that seemed to be broken.

The kit came with a diagram/layout of the electronics and paths on the board, so I started deciphering that as I looked at the board. It all started to click. At this point I started realising “hey there's none incoming, it's something higher up before the second voltage regulator”. This is a super obvious thing to experienced people, I'm sure, but I am just too new and dumb about this stuff.

So anyway, I started chasing the line from the successful 5V output of the first regulator. I finally come to the optional power switch holes on the board. The kit didn't come with a switch so I figured it must be optional. Nope! I was supposed to cut off a couple jumper pins and solder them into the holes, then put a jumper on them. Again, this is likely something super obvious to an experienced person, but that's not me!

So after a quick solder of the two jumper pins and a jumper, I plug in the board. After a second the green light comes on, and the display on the screen appears, although it's very dark. I'll debug that another day though, as I have no keyboard for the device yet (it's coming) and I'm just happy I got the board working!